What it means
Reductant Heater E Control Circuit: the control circuit has an electrical fault. The reductant (DEF/AdBlue) heater keeps the urea fluid from freezing; a fault can impair SCR dosing in cold conditions.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Reductant Heater E is part of the DEF/AdBlue system that helps keep the fluid usable in freezing conditions so the selective catalytic reduction system can dose it into the exhaust. The engine or aftertreatment controller monitors Heater E’s control circuit and sets P223A when it detects an electrical fault in that circuit.
Common causes
Most likely first.
- Open or short in heater control wiring
- Faulty reductant heater element
- Loose or corroded connector
- Fault in the heater control circuit
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
How to diagnose it
- Read freeze-frame data and aftertreatment live data for Reductant Heater E, including commanded state and any related DEF or NOx warnings.
- Locate Heater E using the vehicle wiring information and inspect its connector and harness for corrosion, damage, or contact with hot or moving parts.
- Check related fuses, power feeds, grounds, and connectors for the Heater E circuit using the wiring diagram.
- Test the Heater E control wiring for opens or shorts and check the heater element against the manufacturer's specification.
- If the wiring and element test correctly, follow the manufacturer's diagnostic procedure for the heater control circuit or module.
Common fixes
- Reconnect or clean a loose or corroded Heater E connector.
- Repair damaged, open, or shorted Heater E control wiring.
- Replace a failed reductant Heater E element confirmed by testing.
- Repair a faulty control-circuit power, ground, or driver connection identified by diagnosis.
Can I keep driving?
The vehicle may remain drivable, but in freezing weather DEF may not thaw or dose correctly, increasing NOx emissions and potentially starting a no-start countdown. Check any dashboard countdown or emissions warning promptly and follow the vehicle’s instructions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.